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Snakes are reptiles. Like all reptiles, they are cold-blooded. Another word for this is ectothermic, which means that they cannot produce their own body heat. Instead, they use the sun to heat their bodies and then regulate their temperature with behavior. Because they don't need the energy from food to increase body heat, snakes can eat very little and still survive. In fact, some snakes can go for months between meals, and a few survive by eating just one large meal during a year. When they do eat, snakes swallow their prey whole. They do this with specialized jaws that enable them to swallow animals that are even bigger than their own heads!
Poison
Lots of snakes inject their prey with poisonous venom. These venomous snakes strike out and bite their prey. The poison can paralyze the prey, so it cannot move, or even kill it. Snakes make venom in special salivary glands in their upper jaw that contain a mixture of poisons. Some of these poisons are just to kill the prey, but other chemicals break down the inner organs of the prey, so it's easier to digest.
Snakes inject venom through two hollow teeth called fangs. In most snakes, the fangs are folded flat against the roof of its mouth, and when the snake is ready to strike, it points them outward. In some poisonous snakes, like cobras and coral snakes, the fangs are always out, but short enough so when the snake closes its mouth it doesn't bite itself!
One group of snakes spit or eject venom in a spray, instead of biting! These snakes use their poison for self-defense instead of for getting food. They aim their spray at the eyes of their enemies, and can sometimes reach their target from 8 feet away.
Skin
The body of snakes are covered in overlapping scales. These scales are made up of keratin, which is the same protien material that makes up animal's horns. Scales main purpose is to prevent water loss. The color and pattern of snakes is determined by pigment cells in the skin layer below the scales. This means every year when snakes shed their top scalely layer of skin, they keep their coloration. To help with camoflage, most snakes display drab earth tone colors to blend with their natural surroundings. But others are brightly colored to warn predators they are venomous.
Moving
Even though snakes don't have legs, they have many ways to move. The most common type of snake movement is called lateral undulation, where the snake alternately tightens and relaxes a set of muscles along each side of its body to produce horizontal waves that travel down the body. At the same time the muscles are doing this, the snake's tail pushes against the ground. Sounds confusing, right? But some snakes can reach speeds of 6 mph using lateral undulation. Lots of snakes can also climb. These snakes, known as tree-climbing snakes, use the same movement as earthworms, called concertina movement. To do this, these snakes coil their tails around a tree, then hook their necks into a higher part of the tree and pull the rest of their bodies up behind them. Larger snakes, such as pythons, use something called rectilinear locomotion. When a snake does this, it extends the scales under it's belly into the ground, and then push against them with it's ribs. The last way snakes move is by sidewinding. To do this, a snake makes an arc with the front part of its body and throws its head forward, so that it travels through the air before touching the sand. The snake then pulls the back part of its body into line with its head before moving again.
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